Captain Peter Moore is silhouetted against the southern Indian Ocean aboard a Royal Australian Air Force AP-3C Orion aircraft searching for the missing Malaysia Airlines flight 370 over the southern Indian Ocean on Thursday.

Captain Peter Moore is silhouetted against the southern Indian Ocean aboard a Royal Australian Air Force AP-3C Orion aircraft searching for the missing Malaysia Airlines flight 370 over the southern Indian Ocean on Thursday. (Michael Martina / AFP/Getty Images)

An image released Sunday by the Australian Maritime Safety Authority in Canberra, Australia, shows three search areas in the Indian Ocean, west of Australia, where planes and ships are searching again for the missing Malaysian Airlines Flight 370.

An image released Sunday by the Australian Maritime Safety Authority in Canberra, Australia, shows three search areas in the Indian Ocean, west of Australia, where planes and ships are searching again for the missing Malaysian Airlines Flight 370. (Australian Maritime Safety Authority)

BEIJING — An Australian ship hunting for missing Malaysia Airlines Flight 370 has picked up two more transmissions similar to those of the jet's "black boxes," and the coordinator of the search said Wednesday the "pings" were helping to narrow the search area significantly.

The vessel Ocean Shield, towing an acoustic detection device lent by the U.S. Navy, recorded pings of five and seven minutes' duration Tuesday afternoon and evening, said Air Chief Marshal Angus Houston, who is coordinating the search efforts from Perth, Australia.

Houston said authorities were not ready to deploy a sonar-equipped underwater vessel to scan the seafloor for debris. He noted, however, that the last signal was "very weak" and that the time to deploy the underwater vehicle was "not very far away."

The Ocean Shield can search six times as much area as a submersible can in the same time, Houston said.

"We need to make hay while the sun shines," Houston said. Batteries on the black boxes are designed to last 30 days, and the search entered its 33rd day Wednesday, he noted. The Boeing 777, carrying 239 passengers and crew members, disappeared in the predawn hours March 8 while en route from Kuala Lumpur, Malaysia, to Beijing.

The ocean where the pings were detected is extremely deep — more than 2.5 miles — and analysis shows the seabed has high levels of silt that may be "tens of meters" thick, potentially complicating the search, Houston said.

"We know more about the surface of the moon than our own seabed," said Australian Navy Commodore Peter Leavy.

A plane was deployed Wednesday to drop sonar buoys equipped with hydrophones that descend 1,000 feet below the surface, and which can transmit any sound back to search aircraft via radio, Leavy added.

The search area, about 1,400 miles northwest of Perth, has been "significantly reduced" to about 28,000 square miles, Houston said, enabling a "much more thorough" search.

Houston cautioned that it took 20 days for an underwater search vehicle to locate the wreckage of the Air France flight that plummeted into the Atlantic Ocean off Brazil in 2009, even though searchers had a better fix on the crash site.

BEIJING -- An Australian military plane participating in the search for missing Malaysia Airlines Flight 370 on Thursday detected an underwater acoustic signal that may be from the Boeing 777’s black boxes, Australian authorities said.

BEIJING – A British submarine joined the search Wednesday for the missing Malaysia Airlines jet as Malaysian police said their probe of the 227 passengers found no personal or psychological problems or motivation to hijack or sabotage the aircraft.

BEIJING -- Peter Jackson, the director of the “Lord of the Rings” and “The Hobbit” film series, has lent his personal Gulfstream jet to the team searching for missing Malaysia Airlines Flight 370, Radio New Zealand reported.

BEIJING – From beach vacations to entertainers, all things Malaysian are being boycotted in China in protest of the disappearance of Malaysia Airlines flight 370 and what many consider the bungled investigation that has followed.